This invention relates to a hitching device which is attachable to or in association with a three-point hitch such as a three-point hitch of a tractor and which is adjustable to allow for easy attachment of an implement.
A typical tractor has a drawbar extending rearwardly from the back of the tractor. The drawbar is normally fixed at a particular height. The distance the drawbar extends beyond the back of the tractor is adjustable by a pin arrangement located on the bottom of the tractor chassis. A hitching aperture is formed adjacent the rearward end of the drawbar.
In order to hitch an implement to a tractor, the tractor operator first adjusts the height of the implement so that the implement hitch approximates the height of the drawbar. The height of the hitch is typically adjusted by utilizing a hand-cranked jack. After the operator adjusts the hitch's height to the correct level, the operator then backs the tractor while aligning the rearward end of the drawbar with a clevis located on the forward end of the implement hitch. The hitching aperture is aligned with apertures formed in the implement clevis. A pin is positioned in the aligned apertures to effectuate a connection between the implement and the tractor.
As is apparent, the hitching operation with a fixed height drawbar requires the operator to climb down from the operating platform of the tractor in order to adjust the height of the implement hitch. After the implement hitch has been adjusted, the operator must then climb back up onto the platform and align the drawbar with the implement hitch. If the operator does not adjust the implement hitch height correctly the first time, then he/she may be required to climb off of and back onto the tractor several times in order to perform the hitching operation.
In addition to a drawbar, many tractors have a three-point hitch. The three-point hitch includes a pair of draft links pivotally attached to the tractor chassis. The draft links are spaced apart and disposed at generally the same adjustable vertical height. Each of the draft links is further connected to a lift link along an intermediate portion of the draft link. Each of the lift links is attached to a laterally-disposed hydraulically-actuated rockshaft. As the shaft is actuated upwardly or downwardly, the draft links are also pivoted upwardly or downwardly via the lift links.
The three-point hitch further includes a center link pivotally connected to the tractor chassis at a location above and directly between the draft links. The center link has a connecting hole or hook formed on its rearward end. The connecting holes of the draft links and the center link are aligned with and connected to a corresponding three-point hitch structure located on an implement. After an implement has been attached to the three-point hitch of the tractor, the implement can be raised or lowered by actuating the rockshaft.
A prior art device is available for adapting the three-point hitch for attachment to an implement having a standard hitch with a clevis. This device is called a hitch bar and consists of an elongated bar with pin members extending from each end. The pin members engage the connecting holes in the ends of the draft links so that the elongated bar is supported in a horizontal orientation. The elongated bar has a plurality of hitching apertures along its length to allow adjustable connection of the implement clevis. The operator can adjust the height of the hitch bar by actuating the rockshaft of the three-point hitch.
The use of a hitch bar is disadvantageous for various reasons. First, because the hitch bar is only attached at its ends to each draft link at only one point, the bar can rotate on its longitudinal axis in its horizontally suspended position between the draft links. Incidental rotation of the bar may result in the hitching apertures of the bar not being properly aligned for attachment to the hitch of an implement. Thus, the operator may be required to rotate the bar to its proper position during the connecting operation. Further, the bar may rotate as the tractor pulls an implement attached to the bar. This can result in unwanted stresses and breakage or excessive wear in the bar, connecting pin, and implement hitch clevis.
A further disadvantage of the hitch bar is that it moves the connection of the implement to the tractor farther away from the tractor than is typical with a standard drawbar. Because of the nature of the three-point hitch, the connecting holes disposed on the ends of the draft links are positioned a substantial distance behind the end of the drawbar adjusted to its standard length. Thus, the implement is disposed further behind the tractor than is typical. When using an implement that requires connection to the power takeoff (PTO) of the tractor (for example, a baler), attachment of the implement to the hitch bar may require the use of an extra long PTO shaft to supply power to the implement. Increasing the length of the PTO shaft increases the possibility of damage to the shaft and the surrounding structures. Further, oftentimes an operator using a hitch bar with a PTO driven implement inadvertently raises the hitch bar such that it contacts the PTO shaft causing damage thereto.
It is further known within the farming industry that positioning the hitch point of the implement to the tractor at a location that is the center of the PTO shaft is advantageous. This hitching configuration results in a substantially constant driving velocity being conveyed from the tractor through the PTO shaft to the implement even during turning of the tractor. Often times, implements are constructed to provide this configuration with a drawbar adjusted to its standard length. Thus, the extended rearward position of the hitch bar does not allow this advantageous configuration. This can result in velocity fluctuations of the driven mechanisms of the implement.
In addition, tractors are often pressed into service to pull fifth wheel (gooseneck) trailers in conditions where access by a truck is difficult or impossible. Typical hitch bars, however, have no way to elevate the hitch high enough to allow the attachment of a fifth wheel type trailer.
It is often advantageous to have a type of lifting device, such as a fork lift, adapted for attachment to a tractor three point hitch. Typically the connection of such a lifting device would necessitate the removal of any equipment already connected to the three point hitch prior to installation of the lifting device.
It is further advantageous to have a hitching device which is adapted to be connected to a quick-attaching coupler for a three point hitch. The quick-attaching coupler connects to the three point hitch and generally provides three upwardly extending hooks just rearward of the distal end of the draft links and the center link respectively. Once the quick-attaching coupler is connected to the three point hitch the tractor operator can utilize the tractor hydraulic system to couple the quick-attaching coupler to all standard three-point type equipment without having to leave the tractor. One or more of the hooks is provided with a latch mechanism to prevent uncoupling of the three-point type equipment from the coupler until the latch is released by the tractor operator.
Thus, a hitching device is needed which can be attached to the three-point hitch, or to a quick-attaching coupler already attached to the three-point hitch, to allow adjustment of the vertical height of the hitching aperture relative to the drive vehicle. Further, a hitching device is needed which is stably secured to the three-point hitch so as to prevent inadvertent rotation. Further, a hitching device is needed which allows connection of the implement to a drawbar disposed at its standard length so that it can be driven with a tractor PTO shaft in a normal advantageous manner. The hitching device should allow free, unimpeded access to the PTO drive on the tractor. Further, a hitching device is needed which allows the connection of either a fifth wheel trailer or a standard trailer. Finally, a hitching device is needed which can serve double duty for both hitching and as a fork lift or round bale lift.